U.S. patent application number 13/406912 was filed with the patent office on 2013-08-29 for turbocharged engine canister system and diagnostic method.
This patent application is currently assigned to CHRYSLER GROUP LLC. The applicant listed for this patent is Richard J. Carnaghi, Paul J. Gregor, Christopher G. Hadre, Roger C. Sager. Invention is credited to Richard J. Carnaghi, Paul J. Gregor, Christopher G. Hadre, Roger C. Sager.
Application Number | 20130220282 13/406912 |
Document ID | / |
Family ID | 47846183 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130220282 |
Kind Code |
A1 |
Hadre; Christopher G. ; et
al. |
August 29, 2013 |
TURBOCHARGED ENGINE CANISTER SYSTEM AND DIAGNOSTIC METHOD
Abstract
An evaporative emission control system for a turbocharged
engine. The system includes a fuel vapor canister in fluid
communication with an intake manifold of the engine, a purge valve
positioned between the intake manifold and the canister, a bypass
valve positioned between the purge valve and the canister and
connected to the atmosphere, and an evaporative system integrity
monitor operable to seal the canister from the atmosphere when the
engine is off. In operation, the monitor is closed so as to seal
the canister from the atmosphere, the purge valve is closed so as
to isolate the intake manifold from the canister, and the bypass
valve is opened so as to connect the canister to the atmosphere.
Proper operation of the monitor is determined if the monitor
toggles from closed to open when a vacuum in the fuel vapor
canister reaches a predetermined level.
Inventors: |
Hadre; Christopher G.;
(LaSalle, CA) ; Sager; Roger C.; (Munith, MI)
; Gregor; Paul J.; (Dexter, MI) ; Carnaghi;
Richard J.; (Macomb, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hadre; Christopher G.
Sager; Roger C.
Gregor; Paul J.
Carnaghi; Richard J. |
LaSalle
Munith
Dexter
Macomb |
MI
MI
MI |
CA
US
US
US |
|
|
Assignee: |
CHRYSLER GROUP LLC
Auburn Hills
MI
|
Family ID: |
47846183 |
Appl. No.: |
13/406912 |
Filed: |
February 28, 2012 |
Current U.S.
Class: |
123/520 ;
73/114.69 |
Current CPC
Class: |
F02M 25/089 20130101;
F02M 25/0836 20130101; F02M 25/0809 20130101 |
Class at
Publication: |
123/520 ;
73/114.69 |
International
Class: |
F02M 33/02 20060101
F02M033/02; G01M 15/04 20060101 G01M015/04 |
Claims
1. An evaporative emission control system for a turbocharged engine
comprising: a fuel vapor canister in fluid communication with an
intake manifold of the turbocharged engine; a purge valve
positioned between the intake manifold and the fuel vapor canister;
a bypass valve positioned between the purge valve and the fuel
vapor canister and connected to the atmosphere; and an evaporative
system integrity monitor operable to seal the canister from the
atmosphere when the engine is off.
2. The evaporative emission control system according to claim 1,
further comprising a one-way check valve located between the
manifold and the purge valve and operable to prevent vapor backflow
from the manifold to the canister.
3. The evaporative emission control system according to claim 1,
further comprising a vacuum ejector tee fluidly coupled between the
intake manifold and the purge valve, the vacuum ejector tee having:
a first port in fluid communication with the fuel vapor canister; a
second port in fluid communication with an output of a
turbocharger; and a third port in fluid communication with an input
to the turbocharger.
4. The evaporative emission control system according to claim 3,
further comprising a one-way check valve located between the first
port of the vacuum ejector tee and the purge valve and operable to
prevent vapor backflow from the vacuum ejector tee to the manifold
and the fuel vapor canister.
5. A method of testing operation of an evaporative emission control
system for a turbocharged engine, the method comprising: closing an
evaporative system integrity monitor so as to seal a fuel vapor
canister from the atmosphere when the engine is turned off, the
fuel vapor canister being in fluid communication with an intake
manifold of the turbocharged engine; closing a purge valve between
the intake manifold and the fuel vapor canister so as to isolate
the intake manifold from the fuel vapor canister; opening a bypass
valve between the purge valve and the fuel vapor canister so as to
connect the fuel vapor canister to the atmosphere; and determining
whether the evaporative system integrity monitor toggles from
closed to open when a vacuum in the fuel vapor canister reaches a
predetermined level.
6. The method of testing operation of an evaporative emission
control system according to claim 5, further comprising setting a
malfunction indicator noting that repair is needed when the signal
indicates that the evaporative system integrity monitor did not
toggle from closed to open.
7. A non-transitory computer readable medium for testing operation
of an evaporative system integrity monitor, which when programmed
into a controller of an evaporative emission control system for a
turbocharged engine, causes the controller to: close a purge valve
between an intake manifold and a fuel vapor canister so as to
isolate the intake manifold from the fuel vapor canister; open a
bypass valve between the purge valve and the fuel vapor canister so
as to connect the fuel vapor canister to the atmosphere; and
receive a signal indicating whether the evaporative system
integrity monitor has toggled from closed to open when a vacuum in
the fuel vapor canister reaches a predetermined level.
8. The non-transitory computer readable medium according to claim
7, wherein the controller determines that the evaporative system
integrity monitor is functioning properly when the signal indicates
that the evaporative system integrity monitor toggled from closed
to open.
9. The non-transitory computer readable medium according to claim
7, wherein the controller determines that the evaporative system
integrity monitor is not functioning properly when the signal
indicates that the evaporative system integrity monitor did not
toggle from closed to open.
10. The non-transitory computer readable medium according to claim
9, wherein the controller sets a malfunction indicator noting that
repair is needed when the signal indicates that the evaporative
system integrity monitor did not toggle from closed to open.
Description
FIELD
[0001] The present invention generally relates to evaporative
emission control systems for automotive vehicles and, more
particularly, to a turbocharged engine canister purge system with
diagnostic functionality.
BACKGROUND
[0002] Modern internal combustion engines generate approximately
20% of their hydrocarbon emissions by evaporative means, and as a
result, automobile fuel vapor emissions to the atmosphere are
tightly regulated. For the purpose of preventing fuel vapor from
escaping to the atmosphere an Evaporative Emissions Control (EVAP)
system is typically implemented to store and subsequently dispose
of fuel vapor emissions. The EVAP system is designed to collect
vapors produced inside an engine's fuel system and send them
through an engine's intake manifold into its combustion chamber to
get burned as part of the aggregate fuel-air charge. When pressure
inside a vehicle's fuel tank reaches a predetermined level as a
result of evaporation, the EVAP system transfers the vapors to a
charcoal, or purge canister.
[0003] Subsequently, when engine operating conditions are
conducive, a purge valve located between the intake manifold of the
engine and the canister opens and vacuum from the intake manifold
draws the vapor to the engine's combustion chamber. Thereafter, the
purge canister is regenerated with newly formed fuel vapor, and the
cycle continues.
[0004] As opposed to vacuum in naturally aspirated applications, at
higher throttle levels a turbocharged/supercharged engine's intake
manifold can see relatively high boost pressures generated by
forced induction. Under this condition, a one-way check valve can
be used to prevent backflow through the EVAP system and furthermore
a vacuum ejector tee can be used to provide vacuum for purge
flow.
[0005] In addition to a fuel vapor recovery function, an EVAP
system may perform a leak-detection function. To that end, a known
analog leak-detection scheme employs an evaporative system
integrity monitor (ESIM) switch which stays on if the system is
properly sealed, and toggles off when a system leak is detected.
When the ESIM switch fails to toggle under specific conditions, an
engine control unit (ECU) detects this situation and alerts an
operator of the vehicle with a malfunction indicator.
[0006] Furthermore, an EVAP system's ability to detect leaks can be
regularly verified in engine key-off mode via a so-called
rationality test. Presently known rationality tests confirm the
ESIM switch functionality through a simulated system leak which is
generated by opening the purge valve to relieve a low level of
system vacuum (approximately 0.5 KPa) retained from when the engine
was running. The ECU then detects if the ESIM toggles from on to
off, which is an indicator that the switch is functioning
correctly. For the rationality test to be performed in a
turbocharged/supercharged engine, however, a leak-detection scheme
utilizing an ESIM switch has been heretofore known as requiring a
two-way low airflow communication between the purge valve and the
intake manifold. A simple check-valve does not permit two-way flow,
therefore it will not support both purge flow during boost
operation and ESIM functions in an EVAP system of a
turbocharged/supercharged engine.
SUMMARY
[0007] In one form, the present disclosure provides an evaporative
emission control system for a turbocharged engine that may include
a fuel vapor canister in fluid communication with an intake
manifold of the turbocharged engine, a purge valve positioned
between the intake manifold and the fuel vapor canister, a bypass
valve positioned between the purge valve and the fuel vapor
canister and connected to the atmosphere, and an evaporative system
integrity monitor operable to seal the canister from the atmosphere
when the engine is off.
[0008] In another form, the present disclosure provides a method of
testing operation of an evaporative emission control system for a
turbocharged engine that may include closing an evaporative system
integrity monitor so as to seal a fuel vapor canister from the
atmosphere when the engine is turned off, closing a purge valve
between an intake manifold and the fuel vapor canister so as to
isolate the intake manifold from the fuel vapor canister, opening a
bypass valve between the first purge valve and the fuel vapor
canister so as to connect the fuel vapor canister to the
atmosphere, and determining whether the evaporative system
integrity monitor toggles from closed to open when a vacuum in the
fuel vapor canister reaches a predetermined level.
[0009] In yet another form, the present disclosure provides a
non-transitory computer readable medium for testing operation of an
evaporative system integrity monitor which, when programmed into a
controller of an evaporative emission control system for a
turbocharged engine, causes the controller to close a purge valve
between an intake manifold and a fuel vapor canister so as to
isolate the intake manifold from the fuel vapor canister, open a
bypass valve between the purge valve and the fuel vapor canister so
as to connect the fuel vapor canister to the atmosphere, and
receive a signal indicating whether the evaporative system
integrity monitor has toggled from closed to open when a vacuum in
the fuel vapor canister reaches a predetermined level.
[0010] Further areas of applicability of the present disclosure
will become apparent from the detailed description, drawings and
claims provided hereinafter. It should be understood that the
detailed description, including disclosed embodiments and drawings,
are merely exemplary in nature, intended for purposes of
illustration only, and are not intended to limit the scope of the
invention, its application or use. Thus, variations that do not
depart from the gist of the invention are intended to be within the
scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic diagram of an evaporative emission
control system according to an aspect of the present invention;
[0012] FIG. 2 is a schematic diagram of the evaporative emission
control system of FIG. 1 in vacuum purge mode;
[0013] FIG. 3 is a schematic diagram of the evaporative emission
control system of FIG. 1 in boost purge mode; and
[0014] FIG. 4 is a schematic diagram of the evaporative emission
control system of FIG. 1 in ESIM switch rationality test mode.
DETAILED DESCRIPTION
[0015] Referring now to the drawings in which like elements of the
invention are identified with identical reference numerals
throughout, FIG. 1 shows an evaporative emission control system 10
of a turbocharged/supercharged engine 11. The evaporative emission
control system 10 includes a fuel tank 12 including a fuel fill
tube 14 which is sealed by a cap 16. The fuel tank 12 is fluidly
coupled to a carbon filled canister 18 by a fuel tank vapor conduit
20. The canister 18 is fluidly coupled to an intake manifold 22 by
a canister vapor conduit 24. A solenoid activated purge valve 26 is
disposed along the conduit 24 for selectively isolating the
canister 18 and fuel tank 12 from the manifold 22. The canister
vapor conduit 24 also includes a one-way check valve 25 which
prevents fluid (e.g. fuel vapor) backflow from the manifold 22 to
the canister 18. A vent line 28 is coupled to the canister 18 and
terminates at a filter 30 which communicates with the atmosphere.
An evaporative system integrity monitor (ESIM) 32 is disposed
between the canister 18 and the filter 30.
[0016] The canister vapor conduit 24 is branched at a first
location between the purge valve 26 and the canister 18 with a
vacuum bypass conduit 34 and terminates at a filter 36 which
communicates with the atmosphere. A solenoid activated bypass valve
38 is disposed along canister vacuum bypass conduit 34 for
selectively isolating the canister 18 and fuel tank 12 from the
filter 36.
[0017] The canister vapor conduit 24 is also branched at a second
location between the intake manifold 22 and the purge valve 26 with
an ejector tee conduit 40. The ejector tee conduit 40 is connected
to a vacuum ejector tee 42. The ejector tee conduit 40 also
includes a one-way check valve 44 which prevents vapor backflow
from the vacuum ejector tee 42 to the manifold 22 and the canister
18.
[0018] The vacuum ejector tee 42 includes a first port 46 in fluid
connection with ejector tee conduit 40, a second port 48 in fluid
connection with an output from a turbocharger/supercharger 52, and
a third port 50 in fluid connection with an inlet side of the
turbocharger/supercharger 52 an outlet of an air box 54 of the
turbocharger/supercharger 52. In an exemplary embodiment, vacuum
ejector tee 42 is made from a material that is resistant to a
hydrocarbon environment. In an embodiment, it may be made from an
engineering plastic.
[0019] The evaporative emission control system 10 also includes a
controller 56. In an exemplary embodiment, the controller includes
software (e.g., non-transitory computer readable medium) for
determining whether the engine 11 is off or on, controlling the
purge valve 26 and bypass valve 38, reading the state of the vacuum
switch of the ESIM 32 indicating whether the ESIM 32 is functioning
properly during an engine off condition, and setting a malfunction
indicator noting that repair to the ESIM 32 is needed if the ESIM
32 did not toggle from closed to open during the functionality
test.
[0020] Operation of the system 10 is shown in FIGS. 2-4, which
denote the three modes of operation, vacuum purge mode, boost purge
mode, and the ESIM test mode, respectively.
[0021] In vacuum purge mode shown in FIG. 2, the turbocharger 52 is
not operational and a vacuum created in intake manifold 22 by
operation of the engine 11 draws vapor from the canister 18 through
the vapor conduit 24 for consumption in the engine 11. In vacuum
purge mode, the purge valve 26 is open, the vacuum switch in the
ESIM 32 is closed, and the bypass valve 38 is closed by the
controller 56. This, in turn, causes check valve 44 to be pulled
closed thereby preventing air flow from vacuum ejector tee 42. This
is the default operating mode of the engine 11 and evaporative
emission control system 10.
[0022] In boost purge mode shown in FIG. 3, turbocharger 52 is
placed in operation, purge valve 26 is open, the vacuum switch in
the ESIM 32 is closed, and bypass valve 38 is normally closed.
Operation of the turbocharger 52 causes airflow from air box 54
through turbocharger 52 and into manifold 22 creating high pressure
to the intake manifold. Check valve 25 closes when exposed to the
high pressure, thus preventing backflow. This airflow also causes
airflow into port 48 and out of port 50 of vacuum ejector tee 42.
This creates a pressure differential in vacuum ejector tee 42 and
causes a vacuum to be drawn across port 46 due to a Venturi effect.
Due to this vacuum, vapor flows from canister 18 through vapor
conduit 24 and into vacuum ejector tee 42 via ejector tee conduit
40. Vapor from canister 18 is then supplied to the inlet of the
turbocharger 52 or the air box 54 through port 50 of vacuum ejector
tee 42 and routed to the manifold 22 via the turbocharger 52 for
consumption by the engine 11.
[0023] In ESIM test mode shown in FIG. 4, the engine 11 is not in
operation; i.e., in "key-off" condition. In such a "key-off"
condition, a vacuum switch in the ESIM 32 is closed by the residual
vacuum in the system following an "engine on" event, thus sealing
the canister vent line 28. If the evaporative emission control
system 10 is free of leaks, the pressure within the system 10 (and
within canister 18) will go negative due to either cool down from
operating temperatures or during diurnal ambient temperature
cycling. When negative pressure is present within system 10,
testing of the ESIM 32 functionality is started by the controller
56 by closing purge valve 26 and opening bypass valve 38 as shown
in FIG. 4. The opening of bypass valve 38 causes airflow through
filter 36 and vacuum bypass conduit 34 into canister 18 to relieve
the vacuum within canister 18.
[0024] In an exemplary embodiment, the controller 56 is configured
to receive a signal indicating whether the vacuum switch of the
ESIM 32 toggles from closed to open when the vacuum in the canister
reaches a predetermined level after the purge valve 38 is opened.
If the signal indicates that the vacuum switch of the ESIM 32
toggled from closed to open, then the controller 56 indicates that
the ESIM 32 is functioning properly. If ESIM 32 does not toggle to
open, the controller 56 will set a malfunction indicator noting
that repair is needed. In an exemplary embodiment, the controller
includes a non-transitory computer readable medium for testing
operation of the ESIM as discussed herein above.
[0025] Thus, an evaporative emission control system 10 according to
the invention can effectively provide a diagnostic test of the ESIM
in an engine off condition as well as be able to provide canister
purge during both vacuum and boost operating modes of the engine
11.
* * * * *